Caffeine is more soluble in dichloromethane and the both are separated by evaporating the solvent.
Caffeine is an organic plant material which is more soluble in non-polar solvents than in polar solvents. As such, caffeine is more soluble in dichloromethane than in pure water.
In order to carry out a liquid-liquid exaction of dichloromethane from a commercial teabag, the dichloromethane is mixed with water. The caffeine is found to be more soluble in the organic dichloromethane layer than in water.
The two solvents can now be separated using a separating funnel and the solution is evaporated to obtain the caffeine.
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Answer:
- <u>21.4 ml (second choice)</u>
Explanation:
<u>1) Data:</u>
a) C₁ = 60.0% (initial solution)
b) V₁ = 30.0 ml (initial solution)
c) C₂ = 0% (pure water)
d) V₂ = ? (pure water)
e) C₃ = 35.0% (final concentration)
<u>2) Formula:</u>
- C₁V₁ + C₂V₂ = C₃V₃
- V₁ + V₂ = V₃ (assuming volume addtivity)
<u>3) Solution:</u>
<u />
a) Substitute values in the first formula:
- 60.0% × 30 ml + 0 = 35% (30 ml + V₂)
b) Solve the equation (units are supressed just to manipulate the terms)
- V₂ = 7.5 / 0.35 = 21.4 ml ← answer
Answer:
of acetic anhydride is needed
Explanation:
According to balanced equation, 1 mol of salicylic acid completely reacts with 1 mol of acetic anhydride
Number of moles = (mass)/(molar mass)
Molar mass of acetic anhydride = 102.09 g/mol
Molar mass of salicylic acid = 138.121 g/mol
So,
of salicylic acid =
of salicylic acid
Hence,
of salicylic acid reacts completely with
of acetic anhydride.
So, mass of acetic anhydride needed =
= 
Answer:
B) 2.87 L
Explanation:
A mole of any gas at STP has a volume of about 22.412 liters. So, 0.128 moles of gas will have a volume of ...
0.128 · 22.412 L ≈ 2.87 L